This invention relates to pianos. More particularly, it relates to apparatus for controlling the humidity inside pianos.
Changes in relative humidity adversely affects pianos, particularly, due to swelling and contraction of the piano sound board. In geographical regions where humidity swings are substantial, such as, for example, between 20% and 75% relative humidity, pianos which do not have humidity control apparatus must be tuned often, e.g., every few weeks, in order for the pianos to perform properly. In addition, the swelling and contraction of the sound board and other wood parts over time will result in a deterioration of the structural integrity of the entire piano. Thus it is desirable to maintain stabile relative humidity inside of the piano, notwithstanding, swings in relative humidity outside of the piano.
Dampp-Chaser Electronics Corporation ("Dampp-Chaser"), assignee of the present invention, is the leading manufacturer of piano humidity control systems. Dampp-Chaser manufactures piano humidifiers, dehumidifiers and humidistats which are used to control the relative humidity inside of the piano. Examples of Dampp-Chaser's humidity control systems are set forth in its U.S. Pat. Nos. 4,150,372 and 4,423,658, which patents are hereby incorporated herein by reference.
In general, the Dampp-Chaser humidity control apparatus is placed inside of the piano normally adjacent to the sound board and is used in both upright and grand pianos. When humidity is high, the humidistat turns on the dehumidifier and when humidity is low the humidistat turns on the humidifier.
In a few instances, Dampp-Chaser has recommended to its customers that the back of a limited number of pianos, in the case of an upright piano, and the bottom of the piano, in the case of a grand piano, be covered with a sheet made of MYLAR or felt having a plurality of apertures or holes therein, and have provided the materials necessary to accomplish this. It was believed that the holes in the cover were needed to exhaust air with high moisture concentrations from the inside of the piano to the outside of the piano when the dehumidifier was operating and to eliminate the possibility of condensation inside of the piano when the humidifier was operating. In addition, the holes were thought to facilitate the movement of air necessary for the production and the distribution of moist and dry air.
By using the Dampp-Chaser humidification/dehumidification system together with a cover having holes therein, Dampp-Chaser has been able to achieve relative humidity stability inside the piano such that the moisture content of the sound board varied by only 13/4% to 2% when the relative humidity outside of the piano varied between approximately 24% to approximately 70%. While this system has greatly lessened the need to tune the piano frequently, and has resulted in increased structural integrity of the piano, better results are desirable.